The present invention relates to a mill with an impeller, an axial inlet, and a radial outlet and with blades mounted between two disks with the leading edge of each blade projecting into the cross-section of the inlet.
Mills of this type are frequently employed as impeller or impeller-pug mills to mill dry soft coal. The leading edge of the blades in a known mill of this type are perpendicular to the axis of the impeller. The particles of coal that are entrained along with the airflow produced by the impeller in a mill of this type wear down the blades and the peripheral protective cladding on the impeller housing. Wear is especially severe on the surface of the blades that face the inlet and on the peripheral cladding. Such unilateral wear leads to premature breakdown of the blades and cladding.
Skewing the leading edge of the blades to make the wear somewhat more uniform is known in the art.
The object of the present invention is to provide an improvement in a mill of the same type but in which the wear on the blades and cladding is even more uniform.